If the question has out-of-subset application, sure. Not all do.
For example, SGU character questions don't have much application to the rest of the Stargate line of series. SGU and Atlantis have much more, especially later seasons' episodes of Atlantis.
But, for basic Stargate tech questions, yes, it should gain the franchise's tag... especially since that aids in finding duplicates from other series. SGU sheds some additional light on the capabilities of the Stargate network that remained unexplored (to my knowledge) in SG1 and SGA.
A similar situation exists for Buffy and Angel series - one Buffyverse, two series, 13 total seasons, 2 graphic novel series...
Star Trek is one of the worst for that - TOS, TAS, TNG, DS9, Voyager, Enterprise, and several failed proposal TV series; TOS and TNG movies, plus the TOS-Reboot line; Novels for all of the above, plus 5 or 6 novel series with new crews and ships; graphic novels for all the series, plus 5 or 6 additional series with new crews (and no overlap with the novels); plus a series of "technical manuals" of dubious canonicty, but with later ones giving insight into the production staff's understanding of the tech. And then, there are video games, tabletop games, face-to-face roleplaying games....
And the "Star Fleet Universe" by Amarillo Design Bureau, which is an alternate TOS/TAS with 35 years of deviation growth, which looks like ST, sounds like ST, even feels much like ST, is licensed by Paramount and FJD, but isn't actually Star Trek... can't mention any of the crew by name, but can use the races, ships, and equipment of the TOS and TAS properties.
Warp Drive questions for the TOS/TAS stuff are not always going to have broader application - mostly because most of the canon developed after they wrapped, and TNG did retcon-city all over it, as did Enterprise. SFU warp drives have another scale entirely above warp 3.2; everything core released from TNG or later uses the so-called "Modified Cochrane Unit" scale, while TOS and TAS used the "Old Cochrane Unit Scale"... and the terms for these, while widely accepted, appear in the Role-playing games, and then later move into the Tech Manuals. The SFU doesn't even use Warp Factors for speeds above WF 3.2...
And the obscure "Federation Space Battle Manual" which cross fertilized with ADB's Star Fleet Battles had a different approach to Warp drives, too... it also was governed by a license from FJD; it is now sold by ADB for Gamescience.
(FJD :== Franz Joseph Designs).